/*
 * @(#)TargetSection.java
 *
 * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
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package org.wso2.balana.xacml2;

import org.wso2.balana.*;
import org.wso2.balana.ctx.EvaluationCtx;
import org.wso2.balana.ctx.Status;

import java.io.OutputStream;
import java.io.PrintStream;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * This is a container class for instances of <code>TargetMatchGroup</code> and
 * represents the Subjects, Resources, Actions, and Environments sections of an
 * XACML Target. This section may apply to any request.
 * 
 * @since 2.0
 * @author Seth Proctor
 */
public class TargetSection {

	// the list of match groups
	private List matchGroups;

	// the match type contained in this group
	private int matchType;

	// the version of XACML used by the containing Target
	private int xacmlVersion;

	/**
	 * Constructor that takes a group and a version. If the group is null or
	 * empty, then this represents a section that matches any request.
	 * 
	 * @param matchGroups
	 *            a possibly null <code>List</code> of
	 *            <code>TargetMatchGroup</code>s
	 * @param matchType
	 *            the type as defined in <code>TargetMatch</code>
	 * @param xacmlVersion
	 *            the version XACML being used
	 */
	public TargetSection(List matchGroups, int matchType, int xacmlVersion) {
		if (matchGroups == null)
			this.matchGroups = Collections.unmodifiableList(new ArrayList());
		else
			this.matchGroups = Collections.unmodifiableList(new ArrayList(
					matchGroups));
		this.matchType = matchType;
		this.xacmlVersion = xacmlVersion;
	}

	/**
	 * Creates a <code>Target</code> by parsing a node.
	 * 
	 * @param root
	 *            the node to parse for the <code>Target</code>
	 * @param matchType
	 *            the type as defined in <code>TargetMatch</code>
	 * @param metaData
	 *            the meta-data from the enclosing policy
	 * 
	 * @return a new <code>Target</code> constructed by parsing
	 * 
	 * @throws org.wso2.balana.ParsingException
	 *             if the DOM node is invalid
	 */
	public static TargetSection getInstance(Node root, int matchType,
			PolicyMetaData metaData) throws ParsingException {
		List groups = new ArrayList();
		NodeList children = root.getChildNodes();

		for (int i = 0; i < children.getLength(); i++) {
			Node child = children.item(i);
			String name = child.getNodeName();
			String typeName = TargetMatch.NAMES[matchType];

			if (name.equals(typeName)) {
				groups.add(TargetMatchGroup.getInstance(child, matchType,
						metaData));
			} else if (name.equals("Any" + typeName)) {
				// in a schema-valid policy, the Any element will always be
				// the only element, so if we find this we stop
				break;
			}
		}

		// at this point the list is non-empty (it has specific groups to
		// match) or is empty (it applies to any request using the 1.x or
		// 2.0 syntax)
		return new TargetSection(groups, matchType, metaData.getXACMLVersion());
	}

	/**
	 * Returns the <code>TargetMatchGroup</code>s contained in this group.
	 * 
	 * @return a <code>List</code> of <code>TargetMatchGroup</code>s
	 */
	public List getMatchGroups() {
		return matchGroups;
	}

	/**
	 * Returns whether this section matches any request.
	 * 
	 * @return true if this section matches any request, false otherwise
	 */
	public boolean matchesAny() {
		return matchGroups.isEmpty();
	}

	/**
	 * Determines whether this <code>TargetSection</code> matches the input
	 * request (whether it is applicable).
	 * 
	 * @param context
	 *            the representation of the request
	 * 
	 * @return the result of trying to match the target and the request
	 */
	public MatchResult match(EvaluationCtx context) {
		// if we apply to anything, then we always match
		if (matchGroups.isEmpty())
			return new MatchResult(MatchResult.MATCH);

		// there are specific matching elements, so prepare to iterate
		// through the list
		Iterator it = matchGroups.iterator();
		Status firstIndeterminateStatus = null;

		// in order for this section to match, one of the groups must match
		while (it.hasNext()) {
			// get the next group and try matching it
			TargetMatchGroup group = (TargetMatchGroup) (it.next());
			MatchResult result = group.match(context);

			// we only need one match, so if this matched, then we're done
			if (result.getResult() == MatchResult.MATCH)
				return result;

			// if we didn't match then it was either a NO_MATCH or
			// INDETERMINATE...in the second case, we need to remember
			// it happened, 'cause if we don't get a MATCH, then we'll
			// be returning INDETERMINATE
			if (result.getResult() == MatchResult.INDETERMINATE) {
				if (firstIndeterminateStatus == null)
					firstIndeterminateStatus = result.getStatus();
			}
		}

		// if we got here, then none of the sub-matches passed, so
		// we have to see if we got any INDETERMINATE cases
		if (firstIndeterminateStatus == null)
			return new MatchResult(MatchResult.NO_MATCH);
		else
			return new MatchResult(MatchResult.INDETERMINATE,
					firstIndeterminateStatus);
	}

	/**
	 * Encodes this <code>TargetSection</code> into its XML representation and
	 * writes this encoding to the given <code>OutputStream</code> with no
	 * indentation.
	 * 
	 * @param output
	 *            a stream into which the XML-encoded data is written
	 */
	public void encode(OutputStream output) {
		encode(output, new Indenter(0));
	}

	/**
	 * Encodes this <code>TargetSection</code> into its XML representation and
	 * writes this encoding to the given <code>OutputStream</code> with
	 * indentation.
	 * 
	 * @param output
	 *            a stream into which the XML-encoded data is written
	 * @param indenter
	 *            an object that creates indentation strings
	 */
	public void encode(OutputStream output, Indenter indenter) {
		PrintStream out = new PrintStream(output);
		String indent = indenter.makeString();
		String name = TargetMatch.NAMES[matchType];

		// figure out if this section applies to any request
		if (matchGroups.isEmpty()) {
			// this applies to any, so now we need to encode it based on
			// what version of XACML we're using...in 2.0, we encode an Any
			// by simply omitting the element, so we'll only actually include
			// something if this is a 1.x policy
			if (xacmlVersion == XACMLConstants.XACML_VERSION_1_0) {
				out.println(indent + "<" + name + "s>");
				indenter.in();
				out.println(indenter.makeString() + "<Any" + name + "/>");
				indenter.out();
				out.println(indent + "</" + name + "s>");
			}
		} else {
			// this has specific rules, so we can now encode them
			out.println(indent + "<" + name + "s>");

			Iterator it = matchGroups.iterator();
			indenter.in();
			while (it.hasNext()) {
				TargetMatchGroup group = (TargetMatchGroup) (it.next());
				group.encode(output, indenter);
			}
			indenter.out();

			out.println(indent + "</" + name + "s>");
		}
	}

}
